This project has continued studies of intracardiac flow dynamics with digital acquisition and analysis of color Doppler ultrasound imaging techniques for quantifying pathophysiologic hemodynamic abnormalities. Using hydrodynamic principles (jet flux theory, momentum continuity preservation, centerline acceleration, proximal flow convergence and turbulent/viscous interactions), temporal and spatial quantification of flow events is possible. In the clinical management of valvular regurgitation, accurate evaluation of the severity of regurgitation is of major importance. Doppler echocardiographic techniques have enhanced the non invasive assessment of valvular regurgitation. However, there have been, heretofore, no studies related to the clinical applicability of these techniques using strictly quantified reference standards for validation. For this reason the current year's efforts have been applied to mitral and aortic regurgitation. The major areas under investigation have been: 1) regurgitation jet dimensions, 2) regurgitant orifice areas and 3) regurgitant proximal acceleration profiles. Non invasive Doppler methods, thus validated in vivo, provide reliable information about the severity of cardiac valvular regurgitation to aid patient clinical management.